The invention relates to a tamper-indicating closure, as well as to a method and device for the manufacture of a tamper-indicating closure.
Tamper-indicating closures for the closure of containers are widely known and in use. As a rule, this type of closure is provided with a tamper-indicating band which is connected to the closure, by numerous connecting bridges that can be broken by removal of the cap. The tamper-indicating band is held in engagement with the container neck by means of a retention element, in most cases a projecting bead, under-cutting, and/or individual ribs. Additional fastening can, for example, be achieved through heat shrinkage. Combinations of differently shaped retaining elements are also known. The tamper-indicating band can be shaped in such a way, for example in the case of disposable beverage bottles, that it is completely separated from the closure cap and remains on the bottle neck. It is also known, for example from U.S. Pat. No. 5,074,425, to provide a tamper-indicating band with fixed connecting bridges through which the tamper-indicating closure is held after the tearable connecting bridges have been ruptured. These types of tamper-indicating bands are therefore mostly provided with one or more vertical tear lines.
When the container is opened for the first time, the tamper-indicating band is at least temporarily retained on the bottle neck so that, during opening of the closure, the connecting bridges tear and indicate the opening procedure.
These types of closures can be manufactured in one piece together with the tamper-indicating band by the plastic injection molding process. The subsequent application of a weakened line to the closure blanks, between the closure cap and the tamper-indicating band, is also known. These types of devices and methods are known from U.S. Pat. No. 3,673,761 (Leitz/CIBA-Geigy AG), German OS-14 82 603 (Teillac/ALCA S.A.) or U.S. Pat. No. 4,895,265 (LUC et al./The West Co.).
With these closures, the weakened line is applied before or after placing the blank on a container, by means of a cutting tool. A blade, a heated cutting edge or a rotating, circular saw type cutting tool can serve as a cutting tool. The weakening of the material can thus be applied to a warmed closure blank or to cold material. The type of cutting tool and the process parameters, as well as the cutting temperature, depend upon the type of plastic used, the size and type of weakened line, the speed of the process, and so on. Laser cutting tools are also able to be employed with such methods.
On the other hand, metal tamper-indicating closures are also known, onto which a tamper-indicating element is subsequently fastened. The tamper-indicating element is here, as a rule, annularly formed with an initial holding section with which it can be brought into interlocking contact with the closure cap. The holding section--and with it the closure cap--is connected with the tamper-indicating band by means of connecting bridges.
Also known are other methods of manufacture of tamper-indicating closures, such as compression molding, co-injection molding and the like.
A difficulty with these types of closures is that the connecting bridges on the one hand must be formed to be sufficiently stable, so as not to be destroyed or damaged, neither during ejection from the tool, nor during storage, handling or placement of the closure onto a container. On the other hand, the badges should tear or break reliably with the slightest possible manipulation, and in any event when opening for the first time or when attempting to open. Therefore a tamper-indicating band is known, for example from U.S. Pat. No. 4,322,009 (Mumford/Owens-Illinois Inc.), the connecting bridges of which are so created with the same thickness and dimensions that the tamper-indicating band and the tamper-indicating closure are separated from one another by a narrow slot and can come into contact with one another when the cap is screwed onto the container.
A tamper-indicating closure is known, U.S. Pat. No. 5,074,425 (Wustman et al./Crown Cork AG), in which the connecting bridges are weakened on a side which is oriented toward the tearing position.